Dendrite-Free Lithium Metal Battery Enabled by Dendritic Mesoporous Silica Coated Separator

Concentration polarization-induced lithium dendrites seriously impede the practical application of high-energy-density lithium metal batteries. Porous materials that aim to inhibit lithium dendrites are extensively explored. However, their effects are still limited by the intrinsic features of the pores, especially channel geometry and surface properties. Herein, a separator modification strategy of blocking "dendritic deposition" via "dendritic channels" is proposed. A porous shield-like film is formed on the polypropylene separator through the close packing of ultra-small (approximate to 100 nm) silica nanospheres with unique dendritic mesopores (DMS). Besides the hierarchical pores homogenizing the ion flux, the DMS film also provides abundant Si(OH)(x) groups, preferentially adsorbing the TFSI- in the electrolyte and accelerating the transport of Li+. Most notably, the dendritic mesochannels with high complexity can diversify the growth directions of lithium and contribute to a more substantial homogenizing process of Li+. Consequently, a dendrite-free deposition with 1000 stable cycles in Li|Li symmetric cells even at 10 mA cm(-2) is achieved. This study provides a scalable approach for the fabrication of mesoporous separators and offers a fresh perspective on the future design of advanced separators utilized for dendrite suppression.